<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        body{
            width: 1500px;
            height: 1000px;
        }
        main{
            margin-top: 100px;
            height: 500px;
            background: #eee;
        
        }
        main>div{
            width: 200px;
            height: 100px;
            background: red;
            margin-top: 10px;
        }
    </style>
</head>
<body>
    <main>
        <div></div>
    </main>
</body>
</html>